Thermal insulating structure and method of manufacturing same



Jan. 26, 1932. H, LlNDSAY 1,842,875

THERMAL I N SK'LATING STRUCTURE AND METHOD OF MANUFACTURING SAME Filed Dec. 14. 1927 2 Sheets-Sheet 1 I I 9 60 J6 J6 a J9 7 L 6 2 2 r I J9 I v I I J0 :z-i" l l Z0 l: 1 J5 Jan. 26, 1932. H. B. LINDSAY 1,842,875

- THERMAL INSULATING STRUCTURE AND METHOD OF MANUFACTURING SAME Filed Dec. 14; 1927 -2 Sheets-Sheet 2 III-[IN :4, 1, v 1 J00 l w Patented J an. 26, 1932 lATENT OFFICE HARVEY IB. LINDSAY, OF STON, ILLINOIS THERMAL INSULATING STRUCTURE AND METHOD OF MANUFACTURING SAME Application filed December 14, 1927. Serial No. 239,889.

My invention relates more particularly to thermal insulating material and the manufacture of the same, one of my objects bein to provide a material which shall be highly e cotive to prevent the transmission of heat therethrough and economical of manufacture; another object is to provide a body of insulating. material which shall be relatively light in weight and of cellular structure, the cells of which are relatively minute with their walls relatively hard and smooth another object is to provide such a cellular body with the gaseous contents thereof in rarified condition to augment resistance to the transmission of heat therethrough; another object is to provide a novel and inexpensive method of and apparatus for producing insulating material, preferably presenting the various characteristics above noted; and other objects as will be manifest from the following description. Referring to the accompanying drawings:

Figure 1 is a view in vertical sectional elevation of one form of apparatus embodying my invention and adapted for the practicing of my improved method,,this section beingtaken at the irregular line 1 on Fig. 2 and viewed in the direction of the arrow. Figure 2 is a section taken at the line 2 on Fig. 1 and viewed in the direction of the arrow. Figure 3 is a view like Fig. 1 of another form of apparatus embodying my invention and by which my improved process may be practiced,

the section beingtaken at the irregular line 3 on Fig. 4 and viewed in the directionof the arrows. Figure 4 is a plan view thereof, with certain parts in section; andFigure 5, afrag-' mentary sectional View taken at the line 5 on Fig. 3 and viewed in the direction of the ar- In the practice of my improved method and in the production of my produ'ct'I heat preferably to a temperature of about 600 or 700 F. material, the greater portion ofwhich, at least, is a metallic silicate such as silicate ofsoda. The material is heated to the temperature referred to through the stages in which 'the material,.under the action'of heat, forms into large bubbles, which eventually break, and the following stage in which the bubbling subsides, and continue the subjection ofthe 1 dry material to this heat 'untilthe mass in resuming bubbling, swells to the desired thickness. It has been found that the second stage of bubbling referred to difiers widely from the first stage thereof particularly as-to the size of the bubbles produced. Heating through the first stage produces large bubbles which eventually break down, whereas continuing the heat as stated and which effects the second-stage bubbling, produces relatively mico {nute bubbles, substantially all of which re- "main unbroken, (as distinguished from a structure produced by subjecting the material to such heat that calcination'and rupture of the cell walls results,) whereby the resultant" 08 body is of cellular structure with the cells thereof relativel minute, and with the inner surfaces thereof relatively smooth and re sistant to-the impact of heat energy. Furthermore, the minute bubbles-being formed by the ex 'ansion of gaseous fluid generated by the su jection of the material to heat, which upon cooling becomes rarified and remains in the cells, enhances the insulating action.

As an example of the material to be used in producing the product, it may comprise the 'following named ingredients in the proportions noted:

A saturated solution of silicate of soda, one pound; dry silicate, of ;'soda, one-sixteenth of go a pound; borax, one-sixteenth of a pound.

The ingredients named are thoroughly mixed together and the resultant mixture then subjected to the heat, as stated. I

Theuse of dry silicate of soda and borax 35 increases the hardness and toughness of the product and causes the walls of the cells thereof to be thicker than in the case of a product made by heat-treating silicate of soda only. It will be understood,however,.that the silicate of soda or the borax may be omitted, but not without sacrificing certain of the idvantages of the product produced by combining the ingredients above mentioned; .and, furthermore, either one of the solids mentioned may be omitted, or the relative proportions varied in either case, but always with the sodium silicate solution in very materialpreponderance. oo

Furthermore, if desired, any suitable metallic silicate may be used alone, or with any other desirable ingredients.

The material may be subjected to the heat stated in any desirable way, as for example by placing it on a plate, as for example of metal, and subjecting the plate to the desired heat, and where desired the material may be introduced into an upright mold having a cavity suitable for producing the desired form of product, and therein subjecting the material to the heat, to form the cellular mass described.

As a preface to the description of the preferred mode of producing the material, it may be stated that the material in the second-stage bubbling or intumescence, passes through various degrees of plasticity, finally becoming very hard and set; and that while the material is in the plastic stage, the bubbles formed within it, in endeavoring to rise to the surface of the mass, distort into relatively long vertical form forming irregular, greatly elongated, tubular cells. Ifthe bodies of material to be produced, and which in practice would be of sheet or relatively flat block form, or tubular, are so molded that the long dimensions of such elongated cells e'xtend substantially perpendicular to those surfaces of the formed body which are at right angles to the heat flow when the bodies are in service,-

the bodies do not function to the maximum degree due to the relatively small number of internal resistance surfaces opposing the heat flow; neither do they function to the maximum degree to render the mass inaeeesible to Water due to the fact that if the surfaces of the body are punctured, these long cells lead water far into the body, nor do they present the maximum strength because of the arrangement of the long cells crosswise of the faces of the body. In accordance with my invention as I prefer to practice it, these relatively long and narrow cells are caused to extend substantially parallel with those surfaces of the body which are disposed crosswise of the heat flow and thus these cells extend crosswise of such flow, and this result is effected, generally stated, by heating the material referred to While in an uprightly disposedmold, those surfaces of the body formed in the mold and which are to extend, when the body is in use, perpendicularly to' the heat flow being formed by the vertical walls of the mold.

Referring to the apparatus shown in Figs. 1 and 2, which involves the use of a mold of a form and size corresponding with a sheet, or plate, like body of such material to be formed, the mold is represented at 6 and is disposed with the side walls of greater area extending upwardly. The mold is shown as formed of a rectangular frame comprising relative-- respectively, and side-forming plates 10, all

of which preferably are of metal, the silicate solution being fed intothe mold cavity through a pipe 12 valved at 13.

The apparatus shown also comprises heating means, represented as of the electric type, for applying heat to the plate members 10, and comprising end members 14 and 15 containing recesses 16 and 17, respectively, at which these members straddle the opposite marginal edges of the mold and permit of relative vertical movement of the mold and heating means, and-upper and lower cross members (not shown) vertically spaced apart and connecting together the members 14 and 15 and located in pairs at opposite sides of the mold. The heating means also comprise pairs 18 and 19 of rolls located at opposite sides of the mold, adjacent the plates 10 between the upper and lower cross members referred to, these-rolls being journalledat stub shafts 20 and 21 thereon in the members 14 and 15.

Located at opposite sides'of the plate members 10 and in position for supplying heat thereto, are elYctrieal heating elements represented' genera 1v at 22, these elements being carried by; the frame formed of the members 14 and the cross members referred to and suitably arranged to heat the plates 10, preferably uniformly, to the desired temperature.

In the arrangement shown, the heat is applied locally to the mold and in the forming of the body in the .mold relative vertical movement of the mold and the heating means is effected to cause the heat to be progressively applied from the lower to the upper portion of the mold, this being effected in the arrangement shown by means of the rack and pinion mechanism illustrated in Fig. 2, and comprising a rack 23 on themold-frame 9 and a pinion 24 meshing therewith and journalled in the member 14, the shaft represented at 25 carrying this pinion being provided with a pulley 26 for driving the gear. Any suitable means for operating the gear may be provided but in the arrangement shown it is contemplated that it be dri en by power applied froma driving belt engaging the pulley 26. To minimize frlction, the member 15 is provided with a vertical series of horizontally disposed rollers 27 against which the frame 10 bears. It is intended that either the mold or heating means be stationary,vit being preferred that the stationary part be the heating means supported in any suitable manner.

In the use of the apparatus now being described, assuming that the heating-means are stationary the mold member 6 would be raised.by the rack and pinion means to extend at its lower portion opposite the heating elements 22 and the lower portion of the mold cavity charged with the silicate solution through the pipe 12. The heating elements 22 apply to the liquid in the mold the necessary heat for effecting the two stage bubbling hereinbefor referredto, resulting in the formation of relatively minute cells which, as the material becomes plastic in its subjection to the heat, elongate vertically as represented at 28, and the material becom ing set in such condition of the bubbles.

'As the formation of the material in the mold, namely, into the cellular condition stated progresses, the material to be subjected to the heat is fed into the mold through the pipe 12 and the mold progressively lowered, whereby the block cellular sheet or plate-like body to be produced, is formed in the mold by a progressive action, and upon the completion of the operation stated the molded cellular body is removed from the mold for use.

Referring now'to-the apparatus shown in Figs. 3, 4 and 5, which is intended for the continuous roduction of the plate or sheetlikebodies, 1t comprises an upright mold represented generally at 29 and open at its top and bottom, this mold being shown as formed of two pairs of endless blades or belts, preferably of pliable metal 30 and 31 which are disposed in a rectangular arrangement to a provide a mold cavity 32. The blades 30 extend about pairs of pulleys 33- and 34, respectively, journalledon shafts 35 and 36 mounted in heads 37'located at opposite sides of the apparatus and supported in any desirable way. I Y

The endless belts 31 are supported on pulleys fixed on shafts 38 likewise journallcd in the frame 37.;

Theendless. belt devices referred to are shown as driven from a single drive connec;

tion shown as a belt pulley 39, driven through a belt (not shown) fromany suitable source of power, this pulley being connected with an extension of one of the shafts 35. The upper ones of the shafts 35, 36 and 38 are connectedtogether through the medium ofv the bevel pinions 40, 41, 42 and 43, and the lower ones of these shafts similarly connected together whereby all of these shafts rotate in unison and at the same speed from a common source of power.

Located at opposite sides of the portions of the endless blades 30 forming the mold walls and in position for supplying heat thereto, are electrical heating elements reppresented generally at 44 and shown as six in number, three at each of the two opposed sides of the mold cavity and arranged in vertically spaced relation with a heat transmitting plate, of any suitable material interposed between each element 44 and the portion of the endless blade 30 which it opposes and extending practically the full width of the latter to effect the substantially uniform heating of the blades throughout their width. The portions of the blade 30 forming walls of the mold cavity arebacked by vertical series of rolls 45 preferably of the same width as these belts and journalled in any suitable way to rotate freely, these rolls serving to prevent bulging of the belts 30 and therefore distortion of the mold walls during the operation of producing the molded cellular body. If desired, the portions of the endless belts 31 forming the'narrow side walls of the mold may be similarly backed to ensure against distortion.

In this arrangement the plate or sheet-like body as it is formed into the desired-cellular condition within the mold described, is fed downwardly by rotation of the endless belts 30 and 31, the silicate solution'being fed into the top of the mold structure through the pipe 46-valved as represented at 47 a pan, such as that shown at 100, being inserted into the mold cavity, prior to the introduction of the silicate solution, to form amold bottom forming member which carries down with the plate or sheet like molded body in the travel of the endless belts. The operation is preferably a continuous one by the continuous operation of the belts 30 and 31, and the feed of the solution through the pipe. 46 is at the rate desired to ensure the proper feed of the solution to the heating means for producing the cellular body referred to, it being understood that the sheet or plate-like body formed within the mold structure may thus be made of any desired length inasmuch as the body formed is continuous, as distinguished from being molded into definite lengths as in the case of the apparatus forming the :ubject of Figs. 1 and 2.

- There may also be installed knives or scrap ers, tangential to the curve of the belts where they commence to travel round the lower ones of the pulleys 33 and 34 and the lower pulleys engaged by the belts '31 for the purpose of smoothly separating the finished molded body from the surfaces of the belts in event of adhesion therebetween.

In the use of this apparatus, as in the case, ofthe apparatus shown in Figs. 1 and 2, the heat ng elements 44 apply to the liquid in the mold the necessary heat for effecting the two-stage bubbling hereinbefore referred to, with the resultant cells in the body being elongated vertically as represented at 28,

and thus with their longer dimensions generally parallel with those surfaces of the sheet or plate-like body which, when the body is installed in position to serve as an insulant, extend normal to the heat flow.

\Vhile I have illustrated and described certain ways in which my improved method may be practiced and have illustrated and described certain apparatus for carrying out my method, I do not wish to be understood as intending to limit the invention thereto as the method may be practiced in other ways and with other apparatus without departing from the spirit of the invention. Furthermore, while I hare shown certain apparatus as involving features of my invention, I do not wish to be understood as intending to limit it thereto as the same may be variously modified. and altered without "departing from the spirit-of the invention,

hat. I claim asnew, and desirclto secure by L'ettrsjiPatent, is:

ing a.. metallic' silicate'and borax, the c'e ls of said body beingminute. and non communi catin I .1

2. is an'insula'nt, a nioldd body comprising silicate'i'pf soda and borax, the 'cell's of said body being minute and non-commu'ni eating. v

3. The method of producing a body of insulating material containing a mass of separate, non-communicating, minute cells, which while laterally confining the material. suflicient to cause it to form intumescence into minute bubbles but insuflicient to vcalcine form which consists in subjecting metallic consists in subjecting-metallic silicate to, heat the material.

4. The method ofprodu'cingaabody of m-' sulating material contalninga mass of sepabut not substantial 'in excess of, about-600 or 700 F. for aperiod of time insufiicient to produce calcination. U

5. The method of'nroducing a body of insulating material containing a mass of separate, non-connnunicatin.g, minute cells, which consists in subjecting-material comprising metallic silicate to heat sufiici'ent to cause the material to form by intumescence into minute bubbles but insuiiicient to calcine the material. i

. 6. The method of producing a body of insulating material containing a mass of separate, non-communicatin minute cells, which consists in subjecting material comprising metallic. silicate and borax to heat sufficient to cause the material to form by intumescence into minute bubbles but insufficient to calcine thematerial.

7. The method of producing a body of insulating material containing a mass of separate, non-communicating, minute cells, which consists in subjecting material comprising metallic silicate and borax to an intumescing operation at a temperature of,

.sulating material containing a mass of sepa- I f .sulatin'g material of minute cellular form 1. As an? nsulant, amolded. body'co prise 'tvhichcon'sists in subjecting metallic silicate to heat sufficient to cause it to form by intu- 7 sulating material of minute cellular form 80 which consists in progressively applying to a moldcontaining metallic silicate from its bottom toward its top heat sufiicient to cause the material-to form into minute bubbles 12. The method of producing a relatively thin body of insulating material of cellular silicate to heat progressively applied from its bottom toward its top to cause it to bubble rate, non-communicating,minute cells, which while confined in a suitable mold disposed with its faces of larger area extending upwardly.

13. The method of producing a relatively thin body of insulating material of cellular form which consists in progressively applymg to a mold from its bottom toward its top with its faces of larger areas extending upwardly and containing metallic silicate, heat sufficient to cause the silicate to bubble.

14. The method of producing a body of insulating material containing a mass of separate, non-communicating, minute cells which consists in subjecting metallic silicate in solution to heat sufiicient to cause it to form by intumescence into minute bubbles, but insuiiicient to calcine the material.

15. The method of producing a body of insulating material of minute cellular form which consists in' progressively feeding material comprising metallic silicate into a mold and progressively applying to said mold from its bottom toward its top heat suflicient to cause the material to form into minute bubbles while laterally confining the material. 215

16. The method of producing a relatively thin body of insulating material of cellular form which consists in progressively feeding material comprising metallic silicate into a mold disposed with its faces of larger area extending upwardly, and progressively applying to the upwardly extending walls of said mold from 'the bottom toward the top thereof heat sufiicient to cause the material to form into bubbles.

17. The method of producing a body of insulating material containing amass of separate, non-communicating, minute cells, which consists in subjecting metallic silicate in a mold to heat insufiicient to calcine the ma-' 1:50

terial but suflieient to cause it to form by in tumescence into minute non-communicating bubbles of elongated form with their long' dimensions extending generally parallel with those faces of the b0 y of larger area and which are disposed normal to the heat flow when installed for use.

18. The method of producing a body of insulating material containing a mass of separate, non-communicating, minute cells, which consists in subjecting material comprising metallic silicate and borax in a mold to heat insuflicient to calcine the material but sufiieient to cause it to form by intumescence into minute non-communicating bubbles of elongated form with their long dimensions extending generally parallel with those faces of the body of larger area and which are disosed normal to the heat flow when installed or use.

HARVEY B. LINDSAY. 

